Multiparametric MRI - local staging of prostate cancer and beyond

Can we predict pathology without surgery? Weighing the added value of multiparametric MRI and whole prostate radiomics in integrative machine learning models

OBJECTIVE

To test the ability of high-performance machine learning (ML) models employing clinical, radiological, and radiomic variables to improve non-invasive prediction of the pathological status of prostate cancer (PCa) in a large, single-institution cohort.

METHODS

Patients who underwent multiparametric MRI and prostatectomy in our institution in 2015-2018 were considered; a total of 949 patients were included. Gradient-boosted decision tree models were separately trained using clinical features alone and in combination with radiological reporting and/or prostate radiomic features to predict pathological T, pathological N, ISUP score, and their change from preclinical assessment. Model behavior was analyzed in terms of performance, feature importance, Shapley additive explanation (SHAP) values, and mean absolute error (MAE). The best model was compared against a naïve model mimicking clinical workflow.

RESULTS

The model including all variables was the best performing (AUC values ranging from 0.73 to 0.96 for the six endpoints). Radiomic features brought a small yet measurable boost in performance, with the SHAP values indicating that their contribution can be critical to successful prediction of endpoints for individual patients. MAEs were lower for low-risk patients, suggesting that the models find them easier to classify. The best model outperformed (p ≤ 0.0001) clinical baseline, resulting in significantly fewer false negative predictions and overall was less prone to under-staging.

CONCLUSIONS

Our results highlight the potential benefit of integrative ML models for pathological status prediction in PCa. Additional studies regarding clinical integration of such models can provide valuable information for personalizing therapy offering a tool to improve non-invasive prediction of pathological status.

CLINICAL RELEVANCE STATEMENT

The best machine learning model was less prone to under-staging of the disease. The improved accuracy of our pathological prediction models could constitute an asset to the clinical workflow by providing clinicians with accurate pathological predictions prior to treatment.

KEY POINTS

• Currently, the most common strategies for pre-surgical stratification of prostate cancer (PCa) patients have shown to have suboptimal performances. • The addition of radiological features to the clinical features gave a considerable boost in model performance. Our best model outperforms the naïve model, avoiding under-staging and resulting in a critical advantage in the clinic. •Machine learning models incorporating clinical, radiological, and radiomics features significantly improved accuracy of pathological prediction in prostate cancer, possibly constituting an asset to the clinical workflow.

The Sensitivity and Specificity of Multiparametric Magnetic Resonance Imaging and Prostate-Specific Membrane Antigen Positron Emission Tomography/Computed Tomography for Predicting Seminal Vesicle Invasion in Clinically Significant Prostate Cancer: A Multicenter Retrospective Study

Background/Objectives: The presence of seminal vesicle invasion (SVI) in prostate cancer (PCa) is associated with poorer postoperative outcomes. This study evaluates the predictive value of magnetic resonance imaging (MRI) and prostate-specific membrane antigen positron emission tomography/computed tomography (PSMA PET/CT) for SVI in PCa. Methods: This cohort study included consecutive robotic prostatectomy patients for PCa at three Australian tertiary referral centres between April 2016 and September 2022. MRI and PSMA PET/CT results, clinicopathological variables, including age, BMI, prostate-specific antigen (PSA), PSA density, DRE, Biopsy Gleason score, Positive biopsy cores, PIRADS v2.1 score, MRI volume and MRI lesion size were extracted. The sensitivity, specificity, and accuracy of MRI and PSMA PET/CT for predicting SVI were compared with the histopathological results by receiver operating characteristic (ROC) analysis. Subgroup univariate and multivariate analysis was performed. Results: Of the 528 patients identified, 86 had SVI on final pathology. MRI had a low sensitivity of 0.162 (95% CI: 0.088-0.261) and a high specificity of 0.963 (95% CI: 0.940-0.979). The PSMA PET/CT had a low sensitivity of 0.439 (95% CI: 0.294-0591) and a high specificity of 0.933 (95% CI: 0.849-0.969). When MRI and PSMA PET/CT were used in combination, the sensitivity and specificity improved to 0.514 (95%CI: 0.356-0.670) and 0.880 (95% CI: 0.813-0.931). The multivariate regression showed a higher biopsy Gleason score (p = 0.033), higher PSA (p < 0.001), older age (p = 0.001), and right base lesions (p = 0.003) to be predictors of SVI. Conclusions: MRI and PSMA PET/CT independently underpredicted SVI. The sensitivity and AUC improved when they were used in combination. Multiple clinicopathological factors were associated with SVI on multivariate regression and predictive models incorporating this information may improve oncological outcomes.

MRI assessment of seminal vesicle involvement by prostate cancer using T2 signal intensity and volume

BACKGROUND

Seminal vesicle involvement (SVI) in patients with newly diagnosed prostate cancer is associated with high rates of treatment failure and tumor recurrence; correct identification of SVI allows for effective management decisions and surgical planning.

METHODS

This single-center retrospective study analyzed MR images of the seminal vesicles from patients undergoing radical prostatectomy with confirmed T3b disease, comparing them to a control group without SVI matched for age and Gleason grade with a final stage of T2 or T3a. Seminal vesicles were segmented by an experienced uroradiologist, "raw" and bladder-normalized T2 signal intensity, as well as SV volume, were obtained.

RESULTS

Among the 82 patients with SVI, 34 (41.6%) had unilateral invasion, and 48 (58.4%) had bilateral disease. There was no statistically significant difference in the degree of distension between normal and involved seminal vesicles (P = 0.08). Similarly, no statistically significant difference was identified in the raw SV T2 signal intensity (P = 0.09) between the groups. In the 159 patients analyzed, SVI was prospectively suspected in 10 of 82 patients (specificity, 100%; sensitivity, 12.2%). In all these cases, lesions macroscopically invaded the seminal vesicle, and the raw T2 signal intensity was significantly lower than that in the SVI and control groups (P = 0.02 and 0.01).

CONCLUSION

While signal intensity measurements in T2-weighted images may provide insight into T3b disease, our findings suggest that this data alone is insufficient to reliably predict SVI, indicating the need for further investigation and complementary diagnostic approaches.

What the urologist needs to know before radical prostatectomy: MRI effective support to pre-surgery planning

BACKGROUND

Radical prostatectomy (RP) is recommended in case of localized or locally advanced prostate cancer (PCa), but it can lead to side effects, including urinary incontinence (UI) and erectile dysfunction (ED). Magnetic resonance imaging (MRI) is recommended for PCa diagnosis and staging, but it can also improve preoperative risk-stratification.

PURPOSE

This nonsystematic review aims to provide an overview on factors involved in RP side effects, highlighting anatomical and pathological aspects that could be included in a structured report.

EVIDENCE SYNTHESIS

Considering UI evaluation, MR can investigate membranous urethra length (MUL), prostate volume, the urethral sphincter complex, and the presence of prostate median lobe. Longer MUL measurement based on MRI is linked to a higher likelihood of achieving continence restoration. For ED assessment, MRI and diffusion tensor imaging identify the neurovascular bundle and they can aid in surgery planning. Finally, MRI can precisely describe extra-prostatic extension, prostate apex characteristics and lymph-node involvement, providing valuable preoperative information for PCa treatment.

CONCLUSIONS

Anatomical principals structures involved in RP side effects can be assessed with MR. A standardized MR report detailing these structures could assist urologists in planning optimal and tailored surgical techniques, reducing complications, and improving patients' care.

Current Applications of PET/MR: Part II: Clinical Applications II

Due to the major improvements in the hardware and image reconstruction algorithms, positron emission tomography/magnetic resonance imaging (PET/MR) is now a reliable state-of-the-art hybrid modality in medical practice. Currently, it can provide a broad range of advantages in preclinical and clinical imaging compared to single-modality imaging. In the second part of this review, we discussed the further clinical applications of PET/MR. In the chest, PET/MR has particular potential in the oncology setting, especially when utilizing ultrashort/zero echo time MR sequences. Furthermore, cardiac PET/MR can provide reliable information in evaluating myocardial inflammation, cardiac amyloidosis, myocardial perfusion, myocardial viability, atherosclerotic plaque, and cardiac masses. In gastrointestinal and hepato-pancreato-biliary malignancies, PET/MR is able to precisely detect metastases to the liver, being superior over the other imaging modalities. In genitourinary and gynaecology applications, PET/MR is a comprehensive diagnostic method, especially in prostate, endometrial, and cervical cancers. Its simultaneous acquisition has been shown to outperform other imaging techniques for the detection of pelvic nodal metastases and is also a reliable modality in radiation planning. Lastly, in haematologic malignancies, PET/MR can significantly enhance lymphoma diagnosis, particularly in detecting extra-nodal involvement. It can also comprehensively assess treatment-induced changes. Furthermore, PET/MR may soon become a routine in multiple myeloma management, being a one-stop shop for evaluating bone, bone marrow, and soft tissues.

Prostate Cancer Local Staging with Magnetic Resonance Imaging

Accurate determination of the local stage of prostate cancer is crucial for treatment planning and prognosis. The primary objective of local staging is to distinguish between organ-confined and locally advanced disease, with the latter carrying a worse clinical prognosis. The presence of locally advanced disease features of prostate cancer, such as extra-prostatic extension, seminal vesicle invasion, and positive surgical margin, can impact the choice of treatment. Over the past decade, multiparametric MRI (mpMRI) has become the preferred imaging modality for the local staging of prostate cancer and has been shown to provide accurate information on the location and extent of disease. It has demonstrated superior performance compared to staging based on traditional clinical nomograms. Despite being a relatively new technique, mpMRI has garnered considerable attention and ongoing investigations. Therefore, in this review, we will discuss the current use of mpMRI on prostate cancer local staging.

Clinical stage and grade migration of localized prostate cancer at diagnosis during the past decade

OBJECTIVES

Early 2010s data suggest a reverse stage and grade migration towards more aggressive prostate cancer (PCa) at diagnosis, accelerated by the 2012 US Preventive Services Task Force recommendation against PSA screening. Using the National Cancer Database, we investigated the impact of the 2018 USPSTF recommendation and the COVID-19 outbreak on this shift. We hypothesized that the COVID-19 outbreak would further contribute to a stage and grade migration towards more aggressive disease.

MATERIAL AND METHODS

We identified men with localized PCa diagnosed between 2010 and 2020. We analyzed the shift in the proportion of PCa stratified according to D'Amico risk classification. We used multivariable logistic regression models to assess the association between year of diagnosis and dichotomous variables related to clinical stage and grade of PCa. Predicted probabilities with 95% CI were computed through marginal effect analyses.

RESULTS

We identified 910,898 men with localized PCa. The proportion of low-risk PCa almost halved from 34.9% in 2010 to 17.7% in 2020 (P < 0.001). Compared to 2010, we found in each year increased odds of: PSA≥10 ng/dL starting from 2012 (aOR2012 1.05; 95% CI, 1.02-1.08); cT3-T4 starting from 2015 (aOR2015 1.10; 95% CI, 1.03-1.17); ISUP GG 3-5 starting from 2011 (aOR2011 1.06; 95% CI, 1.03-1.08); and consequently, D'Amico intermediate/high-risk class starting from 2011 (aOR2011 1.03; 95% CI, 1.01-1.05). Fluctuations in the probabilities of PSA≥10 ng/dL and cT3-T4 at diagnosis were observed over time (all P < 0.001). The probability of PSA≥10 ng/dL peaked at 29.0% (95% CI, 28.0%-29.0%) in 2018, while the probability of cT3-T4 peaked at 3.7% (95% CI, 3.6%-3.8%) in 2020. All other outcome variables demonstrated a consistent upward shift (all P < 0.001), with the highest probabilities in 2020 for ISUP GG 3-5 (42.3%, 95% CI, 41.9%-42.6%) and D'Amico intermediate/high-risk (81.3%, 95% CI, 81.0%-81.6%).

CONCLUSIONS

Our study confirms an enduring shift towards a higher proportion of aggressive PCa at diagnosis, likely influenced by the COVID-19 pandemic. The impact of the 2018 USPSTF PCa screening recommendation on the proportion of aggressive PCa seems restricted and likely affected by the pandemic outbreak. Future investigations should evaluate the long-term effects of the 2018 USPSTF recommendations in the postpandemic setting.

The Development and External Validation of Artificial Intelligence-Driven MRI-Based Models to Improve Prediction of Lesion-Specific Extraprostatic Extension in Patients with Prostate Cancer

Adequate detection of the histopathological extraprostatic extension (EPE) of prostate cancer (PCa) remains a challenge using conventional radiomics on 3 Tesla multiparametric magnetic resonance imaging (3T mpMRI). This study focuses on the assessment of artificial intelligence (AI)-driven models with innovative MRI radiomics in predicting EPE of prostate cancer (PCa) at a lesion-specific level. With a dataset encompassing 994 lesions from 794 PCa patients who underwent robot-assisted radical prostatectomy (RARP) at two Dutch hospitals, the study establishes and validates three classification models. The models were validated on an internal validation cohort of 162 lesions and an external validation cohort of 189 lesions in terms of discrimination, calibration, net benefit, and comparison to radiology reporting. Notably, the achieved AUCs ranged from 0.86 to 0.91 at the lesion-specific level, demonstrating the superior accuracy of the random forest model over conventional radiological reporting. At the external test cohort, the random forest model was the best-calibrated model and demonstrated a significantly higher accuracy compared to radiological reporting (83% vs. 67%, p = 0.02). In conclusion, an AI-powered model that includes both existing and novel MRI radiomics improves the detection of lesion-specific EPE in prostate cancer.

[Prostate cancer-multiparametric MRI and alternative approaches in intervention and therapy planning]

BACKGROUND

In recent years, multiparametric magnetic resonance imaging (mpMRI) of the prostate has gained importance and plays a crucial role in both personalized diagnostics and increasingly in the treatment planning for patients with prostate cancer.

OBJECTIVE

The aim of this study is to present established and innovative applications of MRI in the diagnosis and treatment of localized prostate cancer, evaluating their strengths and weaknesses. Furthermore, it will explore alternative approaches and compare them in a comprehensive manner.

MATERIALS AND METHODS

A systematic literature review on the application of mpMRI for biopsy and therapy planning was conducted.

RESULTS

The integration of modern imaging techniques, especially mpMRI, into the diagnostic algorithm has revolutionized prostate cancer diagnosis. MRI and MRI-guided biopsy detect more significant prostate cancer, with the potential to reduce unnecessary biopsies and the diagnosis of clinically insignificant carcinomas. In addition, MRI provides crucial information for risk stratification and treatment planning in prostate cancer patients, both before radical prostatectomy and during active surveillance.

CONCLUSION

Multiparametric MRI offers significant added value for the diagnosis and treatment of localized prostate cancer. The advancement of MRI analysis, such as the implementation of artificial intelligence algorithms, holds the potential for further enhancing imaging diagnostics.

Cavernous nerve mapping methods for radical prostatectomy

INTRODUCTION

Preserving the cavernous nerves, the main autonomic nerve supply of the penis, is a major challenge of radical prostatectomy. Cavernous nerve injury during radical prostatectomy predominantly accounts for post-radical prostatectomy erectile dysfunction. The cavernous nerve is a bilateral structure that branches in a weblike distribution over the prostate surface and varies anatomically in individuals, such that standard nerve-sparing methods do not sufficiently sustain penile erection ability. As a consequence, researchers have focused on developing personalized cavernous nerve mapping methods applied to the surgical procedure aiming to improve postoperative sexual function outcomes.

OBJECTIVES

We provide an updated overview of preclinical and clinical data of cavernous nerve mapping methods, emphasizing their strengths, limitations, and future directions.

METHODS

A literature review was performed via Scopus, PubMed, and Google Scholar for studies that describe cavernous nerve mapping/localization.

RESULTS

Several cavernous nerve mapping methods have been investigated based on various properties of the nerve structures including stimulation techniques, spectroscopy/imaging techniques, and assorted combinations of these methods. More recent methods have portrayed the course of the main cavernous nerve as well as its branches based on real-time mapping, high-resolution imaging, and functional imaging. However, each of these methods has distinctive limitations, including low spatial accuracy, lack of standardization for stimulation and response measurement, superficial imaging depth, toxicity risk, and lack of suitability for intraoperative use.

CONCLUSION

While various cavernous nerve mapping methods have provided improvements in identification and preservation of the cavernous nerve during radical prostatectomy, no method has been implemented in clinical practice due to their distinctive limitations. To overcome the limitations of existing cavernous nerve mapping methods, the development of new imaging techniques and mapping methods is in progress. There is a need for further research in this area to improve sexual function outcomes and quality of life after radical prostatectomy.

Comprehensive analysis of predictive factors for upstaging in intraprostatic cancer after radical prostatectomy: Different patterns of spread exist in lesions at different locations

BACKGROUND

Accurate assessment of the clinical staging is crucial for determining the need for radical prostatectomy (RP) in prostate cancer (PCa). However, the current methods for PCa staging may yield incorrect results. This study aimed to comprehensively analyze independent predictors of postoperative upstaging of intraprostatic cancer.

METHODS

We conducted a retrospective analysis of data from intraprostatic cancer patients who underwent radical surgery between March 2019 and December 2022. Intraprostatic cancer was defined as a lesion confined to the prostate, excluding cases where multiparameter magnetic resonance imaging (mpMRI) showed the lesion in contact with the prostatic capsule. We assessed independent predictors of extraprostatic extension (EPE) and analyzed their association with positive surgical margin (PSM) status. In addition, based on the distance of the lesion from the capsule on mpMRI, we divided the patients into non-transition zone and transition zone groups for further analysis.

RESULTS

A total of 500 patients were included in our study. Logistic regression analysis revealed that biopsy Gleason grade group (GG) (odds ratio, OR: 1.370, 95% confidence interval, CI: 1.093-1.718) and perineural invasion (PNI) (OR: 2.746, 95% CI: 1.420-5.309) were predictive factors for postoperative EPE. Both biopsy GG and PNI were associated with lateral (GG: OR: 1.270, 95% CI: 1.074-1.501; PNI: OR: 2.733, 95% CI: 1.521-4.911) and basal (GG: OR: 1.491, 95% CI: 1.194-1.862; PNI: OR: 3.730, 95% CI: 1.929-7.214) PSM but not with apex PSM (GG: OR: 1.176, 95% CI: 0.989-1.399; PNI: OR: 1.204, 95% CI: 0.609-2.381) after RP. Finally, PNI was an independent predictor of EPE in the transition zone (OR: 11.235, 95% CI: 2.779-45.428) but not in the non-transition zone (OR: 1.942, 95% CI: 0.920-4.098).

CONCLUSION

PNI and higher GG may indicate upstaging of tumors in patients with intraprostatic carcinoma. These two factors are associated with PSM in locations other than the apex of the prostate. Importantly, cancer in the transition zone of the prostate is more likely to spread externally through nerve invasion than cancer in the non-transition zone.

Diagnostic performance of prediction models for extraprostatic extension in prostate cancer: a systematic review and meta-analysis

PURPOSE

In recent decades, diverse nomograms have been proposed to predict extraprostatic extension (EPE) in prostate cancer (PCa). We aimed to systematically evaluate the accuracy of MRI-inclusive nomograms and traditional clinical nomograms in predicting EPE in PCa. The purpose of this meta-analysis is to provide baseline summative and comparative estimates for future study designs.

MATERIALS AND METHODS

The PubMed, Embase, and Cochrane databases were searched up to May 17, 2023, to identify studies on prediction nomograms for EPE of PCa. The risk of bias in studies was assessed by using the Prediction model Risk Of Bias ASsessment Tool (PROBAST). Summary estimates of sensitivity and specificity were obtained with bivariate random-effects model. Heterogeneity was investigated through meta-regression and subgroup analysis.

RESULTS

Forty-eight studies with a total of 57 contingency tables and 20,395 patients were included. No significant publication bias was observed for either the MRI-inclusive nomograms or clinical nomograms. For MRI-inclusive nomograms predicting EPE, the pooled AUC of validation cohorts was 0.80 (95% CI: 0.76, 0.83). For traditional clinical nomograms predicting EPE, the pooled AUCs of the Partin table and Memorial Sloan Kettering Cancer Center (MSKCC) nomogram were 0.72 (95% CI: 0.68, 0.76) and 0.79 (95% CI: 0.75, 0.82), respectively.

CONCLUSION

Preoperative risk stratification is essential for PCa patients; both MRI-inclusive nomograms and traditional clinical nomograms had moderate diagnostic performance for predicting EPE in PCa. This study provides baseline comparative values for EPE prediction for future studies which is useful for evaluating preoperative risk stratification in PCa patients.

CRITICAL RELEVANCE STATEMENT

This meta-analysis firstly evaluated the diagnostic performance of preoperative MRI-inclusive nomograms and clinical nomograms for predicting extraprostatic extension (EPE) in prostate cancer (PCa) (moderate AUCs: 0.72-0.80). We provide baseline estimates for EPE prediction, these findings will be useful in assessing preoperative risk stratification of PCa patients.

KEY POINTS

• MRI-inclusive nomograms and traditional clinical nomograms had moderate AUCs (0.72-0.80) for predicting EPE. • MRI combined clinical nomogram may improve diagnostic accuracy of MRI alone for EPE prediction. • MSKCC nomogram had a higher specificity than Partin table for predicting EPE. • This meta-analysis provided baseline and comparative estimates of nomograms for EPE prediction for future studies.

Predictors of Extraprostatic Extension in Patients with Prostate Cancer

PURPOSE

To identify effective factors predicting extraprostatic extension (EPE) in patients with prostate cancer (PCa).

METHODS

This retrospective cohort study recruited 898 consecutive patients with PCa treated with robot-assisted laparoscopic radical prostatectomy. The patients were divided into EPE and non-EPE groups based on the analysis of whole-mount histopathologic sections. Histopathological analysis (ISUP biopsy grade group) and magnetic resonance imaging (MRI) (PI-RADS v2.1 scores [1-5] and the Mehralivand EPE grade [0-3]) were used to assess the prediction of EPE. We also assessed the clinical usefulness of the prediction model based on decision-curve analysis.

RESULTS

Of 800 included patients, 235 (29.3%) had EPE, and 565 patients (70.7%) did not (non-EPE). Multivariable logistic regression analysis showed that the biopsy ISUP grade, PI-RADS v2.1 score, and Mehralivand EPE grade were independent risk factors for EPE. In the regression assessment of the models, the best discrimination (area under the curve of 0.879) was obtained using the basic model (age, serum PSA, prostate volume at MRI, positive biopsy core, clinical T stage, and D'Amico risk group) and Mehralivand EPE grade 3. Decision-curve analysis showed that combining Mehralivand EPE grade 3 with the basic model resulted in superior net benefits for predicting EPE.

CONCLUSION

Mehralivand EPE grades and PI-RADS v2.1 scores, in addition to basic clinical and demographic information, are potentially useful for predicting EPE in patients with PCa.

Perineural Invasion and Spread in Common Abdominopelvic Diseases: Imaging Diagnosis and Clinical Significance

Malignancies and other diseases may spread by multiple pathways, including direct extension, hematogenous spread, or via lymphatic vessels. A less-well-understood route is the peripheral nervous system, which is known as perineural spread (PNS). In addition to accounting for pain and other neurologic symptoms, PNS affects both disease prognosis and management. Although PNS is commonly discussed in relation to head and neck tumors, there is emerging data regarding PNS in abdominopelvic malignancies and other conditions such as endometriosis. Due to improved contrast and spatial resolution, perineural invasion, a finding heretofore diagnosed only at pathologic examination, can be detected at CT, MRI, and PET/CT. PNS most commonly manifests as abnormal soft-tissue attenuation extending along neural structures, and diagnosis of it is aided by optimizing imaging parameters, understanding pertinent anatomy, and becoming familiar with the typical neural pathways of spread that largely depend on the disease type and location. In the abdomen, the celiac plexus is a central structure that innervates the major abdominal organs and is the principal route of PNS in patients with pancreatic and biliary carcinomas. In the pelvis, the lumbosacral plexus and inferior hypogastric plexus are the central structures and principal routes of PNS in patients with pelvic malignancies. Although the imaging findings of PNS may be subtle, a radiologic diagnosis can have a substantial effect on patient care. Knowledge of anatomy and known routes of PNS and optimizing imaging parameters is of utmost importance in providing key information for prognosis and treatment planning. © RSNA, 2023 Supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. Quiz questions for this article are available through the Online Learning Center.

Staging of Prostate Cancer: Role of Multiparametric Magnetic Resonance Imaging in Different Risk Classes

Using multiparametric magnetic resonance imaging, it is now possible to diagnose prostate cancer and categorize its risk. As it can accurately determine the extracapsu- lar extension of the tumor, invasion of seminal vesicles, involvement of lymph nodes, and the potential presence of bone metastases, multiparametric magnetic resonance imaging plays a crucial role not only in the diagnosis but also in the local staging of prostate cancer. The patients with a history of negative biopsy/increasing prostate- specific antigen and the existence of further data supporting its use in biopsy-naive patients and active surveillance are the most blatant indications for multiparametric magnetic resonance imaging in guidelines. The traditional clinical examination, pros- tate-specific antigen tests, and systematic biopsy are all enhanced by multiparametric magnetic resonance imaging, which will miss certain cancers due to insufficient size or changes in tissue density. The use of multiparametric magnetic resonance imaging is expected to rise, and further advances in the method will be crucial for the secure adoption of targeted therapeutic ideas. Here, we give a succinct overview of multipa- rametric magnetic resonance imaging's application to the identification and risk clas- sification of prostate cancer.

Literature review: Imaging in prostate cancer

Imaging plays an increasingly important role in the detection and characterization of prostate cancer (PC). This review summarizes the key conventional and advanced imaging modalities including multiparametric magnetic resonance imaging (MRI) and positron emission tomography (PET) imaging and tries to instruct clinicians in finding the best image modality depending on the patient`s PC-stage. We aim to give an overview of the different image modalities and their benefits and weaknesses in imaging PC. Emphasis is put on primary prostate cancer detection and staging as well as on recurrent and castration resistant prostate cancer. Results from studies using various imaging techniques are discussed and compared. For the different stages of PC, advantages and disadvantages of the different imaging modalities are discussed. Moreover, this review aims to give an outlook about upcoming, new imaging modalities and how they might be implemented in the future into clinical routine. Imaging patients suffering from PC should aim for exact diagnosis, accurate detection of PC lesions and should mirror the true tumor burden. Imaging should lead to the best patient treatment available in the current PC-stage and should avoid unnecessary therapeutic interventions. New image modalities such as long axial field of view PET/CT with photon-counting CT and radiopharmaceuticals like androgen receptor targeting radiopharmaceuticals open up new possibilities. In conclusion, PC imaging is growing and each image modality is aiming for improvement.

Acquisition Parameters Influence Diffusion Metrics Effectiveness in Probing Prostate Tumor and Age-Related Microstructure

This study aimed to investigate the Diffusion-Tensor-Imaging (DTI) potential in the detection of microstructural changes in prostate cancer (PCa) in relation to the diffusion weight (b-value) and the associated diffusion length l_D. Thirty-two patients (age range = 50-87 years) with biopsy-proven PCa underwent Diffusion-Weighted-Imaging (DWI) at 3T, using single non-zero b-value or groups of b-values up to b = 2500 s/mm². The DTI maps (mean-diffusivity, MD; fractional-anisotropy, FA; axial and radial diffusivity, D// and D┴), visual quality, and the association between DTI-metrics and Gleason Score (GS) and DTI-metrics and age were discussed in relation to diffusion compartments probed by water molecules at different b-values. DTI-metrics differentiated benign from PCa tissue (p ≤ 0.0005), with the best discriminative power versus GS at b-values ≥ 1500 s/mm², and for b-values range 0-2000 s/mm², when the l_D is comparable to the size of the epithelial compartment. The strongest linear correlations between MD, D//, D┴, and GS were found at b = 2000 s/mm² and for the range 0-2000 s/mm². A positive correlation between DTI parameters and age was found in benign tissue. In conclusion, the use of the b-value range 0-2000 s/mm² and b-value = 2000 s/mm² improves the contrast and discriminative power of DTI with respect to PCa. The sensitivity of DTI parameters to age-related microstructural changes is worth consideration.

Radiologic-pathologic correlation of prostatic cancer extracapsular extension (ECE)

Recent advancements on nerve-sparing robotic prostatectomy allow fewer side effects such as urinary incontinence and sexual dysfunction. To perform such techniques, it is essential for the surgeon to know if the neurovascular bundle is involved. Despite being the gold-standard imaging method for Prostate Cancer (PCa) staging, Magnetic Resonance Imaging (MRI) lacks high specificity for detecting extracapsular extension (ECE). Therefore, it is essential to understand the pathologic aspects of ECE to better evaluate the MRI findings of PCa. We reviewed the normal MRI appearance of the prostate gland and the periprostatic space and correlated them to prostatectomy specimens. The different findings of ECE and neurovascular bundle invasion are exemplified with images of both MRI and histologic specimens.

Surveillance Value of Apparent Diffusion Coefficient Maps: Multiparametric MRI in Active Surveillance of Prostate Cancer

BACKGROUND

This study aims to establish the value of apparent diffusion coefficient maps and other magnetic resonance sequences for active surveillance of prostate cancer. The study included 530 men with an average age of 66, who were under surveillance for prostate cancer. We have used multiparametric magnetic resonance imaging with subsequent transperineal biopsy (TPB) to verify the imaging findings.

RESULTS

We have observed a level of agreement of 67.30% between the apparent diffusion coefficient (ADC) maps, other magnetic resonance sequences, and the biopsy results. The sensitivity of the apparent diffusion coefficient is 97.14%, and the specificity is 37.50%. According to our data, apparent diffusion coefficient is the most accurate sequence, followed by diffusion imaging in prostate cancer detection.

CONCLUSIONS

Based on our findings we advocate that the apparent diffusion coefficient should be included as an essential part of magnetic resonance scanning protocols for prostate cancer in at least bi-parametric settings. The best option will be apparent diffusion coefficient combined with diffusion imaging and T2 sequences. Further large-scale prospective controlled studies are required to define the precise role of multiparametric and bi-parametric magnetic resonance in the active surveillance of prostate cancer.

The impact of local staging of prostate cancer determined on MRI or DRE at time of radical prostatectomy on progression-free survival: A Will Rogers phenomenon

INTRODUCTION

We aimed to test whether the current practice of using mpMRI stage might lead to a Will Rogers phenomenon with a stage migration compared to DRE in men undergoing radical prostatectomy.

MATERIAL AND METHODS

A total of 572 consecutive patients who underwent radical prostatectomy at a single institution (2007-2017) were included. Clinical stage using digital rectal examination was determined on table by the operating surgeon; mpMRI and pathological stage were recorded after tumor board review. Progression-free survival (PFS) was defined as no rising PSA, no adjuvant/salvage treatment, and no metastases or mortality. PFS was compared between groups and a model incorporating mpMRI into the EAU risk groups was created.

RESULTS

Median age was 63 years (IQR 58.5-67) and median PSA was 8.9 ng/ml (IQR 6.5-13.2). Using DRE stage, 20% were NCCN low risk, 43% were intermediate, and 37% high. Median follow-up was 48 months (IQR 22-73). Estimated PFS at 1, 3, and 5 years was 75%, 59%, and 54%, respectively. When comparing PFS between DRE and mpMRI stages, patients deemed T1 (P < 0.01) or T3 (P = 0.03) by mpMRI showed better outcomes than patients staged T1 or T3 by DRE. On univariable analysis lower risk for failure was seen for MRI T1 disease (HR 0.10 95%, CI 0.01-0.73, P = 0.02) or MRI T3 (HR 0.70, CI 0.51-0.97, P = 0.03). On multivariable analysis, only MRI T1 remained a significant predictor (HR 0.08, 95% CI 0.01-0.59, P = 0.01). The subsequent, modified EAU risk model using both DRE and mpMRI performed significantly better than the DRE model.

CONCLUSION

PFS based on mpMRI is not the same as DRE staging. Current risk groups which use DRE should be used with caution in whom local stage is based on mpMRI. Our modified EAU-risk categories can provide greater accuracy.

MRI characteristics of canine prostatic neoplasia

Magnetic resonance imaging (MRI) has been used to evaluate dogs with suspected prostatic neoplasia, however, published studies describing MRI characteristics of canine prostatic neoplasia are currently lacking. The aims of the current retrospective case series study were to describe MRI findings of the pelvic region in dogs with a histopathologic or cytologic diagnosis of prostatic neoplasia. Retrospective analysis of these images was then performed by a board-certified veterinary radiologist for shared imaging characteristics. The most consistent characteristics were heterogeneous hyperintensity of the tumor on T2-weighted images (10/10) and short tau inversion recovery images (10/10), prostatic capsular margin distortion by the tumor (10/10), cavitations (10/10), complete effacement of the prostatic architecture (9/10), neurovascular bundle (NVB) compression or invasion (9/10), heterogeneous isointensity of the tumor on T1-weighted images (9/10), and strong contrast enhancement of the tumor (8/10). Additional features included an overlying pattern of distorted radiating striations (7/10), regional lymphadenomegaly (5/10), mineralization within the mass (5/10), urinary bladder trigone involvement (6/10), and post-prostatic urethral involvement (7/10). These findings supported the use of MRI as an adjunct imaging modality for diagnosis and therapeutic planning of prostatic neoplasia and including prostatic neoplasia as a likely differential diagnosis for dogs with these MRI characteristics.

Transperineal Ultrasound Before and After Prostatectomy: Technical Approach and Description

This study assessed the feasibility of dynamic transperineal ultrasound (TPUS) pre/post-radical prostatectomy (RP). Ninety-eight patients were scanned pre-operatively and at four time-points post-operatively. TPUS was performed in 98 patients using an abdominal transducer at rest, during pelvic floor contraction (PFC) and Valsalva (VS) maneuver in supine and standing positions. Urodynamic evaluations included bladder neck angle at rest/PFC/VS, and degree of bladder neck movement. Pre-operative and post-operative measurements were technically feasible in >85% (supine) and >90% (standing) of patients. TPUS offers a reliable non-invasive dynamic assessment of the pelvic floor post-prostatectomy and may prove a useful adjunct for guiding exercises to preserve continence.

Optimization of prostate cancer patient lymph node staging via the integration of neutrophil-lymphocyte ratios, platelet-lymphocyte ratios, and 68 Ga-PSMA-PET-derived SUVmax values

BACKGROUND

At present, standardized parameters for quantitatively evaluating ⁶⁸ Ga-PSMA-PET/CT outcomes when diagnosing lymph node metastasis in prostate cancer patients are lacking. Inflammatory hematological biomarkers offer value as robust predictors of certain cancer-related outcomes. The present study was thus developed to explore approaches to improving the utility of ⁶⁸ Ga-PSMA-PET/CT for diagnosing lymph node metastasis through the combined evaluation of inflammatory hematological markers in prostate cancer patients.

METHODS

Pretreatment patient details including age, initial TPSA levels, hematological findings, biopsy pathology results (Gleason score and ISUP grouping), radical pathology results, and imaging details were collected. Optimal cutoff values for each predictor then being determined based upon Youden's index, with univariate and multivariate analyses were then used to identify independent predictors of lymph node metastasis and used to construct a nomogram.

RESULT

Independent predictors of lymph node metastasis in this patient cohort included SUVmax (odds ratio [OR]: 30.549, 95% confidence interval [CI]: 10.855-85.973, p < 0.001), neutrophil-lymphocyte ratio (OR:8.221, 95%CI: 1.335-50.614, p = 0.023), platelet-lymphocyte ratio (OR:8.221, 95% CI: 1.335-50.614, p = 0.023), initial TPSA (OR:2.761, 95% CI: 1.132-6.733, p = 0.026), and clinical T-stage (T3 vs. T2, OR:11.332, 95% CI:3.929-32.681, p < 0.001; T4 vs. T2, OR:9.101, 95% CI:1.962-42.213, p = 0.005), with corresponding optimal cutoff values of 2.3 (area under the curve [AUC]: 0.873, sensitivity: 0.736, specificity: 0.902), 1.72 (AUC: 0.558, sensitivity: 0.529, specificity: 0.643), 83.305 (AUC: 0.651, sensitivity: 0.299, specificity: 0.979), and 21.875 (AUC: 0.672, sensitivity: 0.736, specificity: 0.601). Subsequent nomogram construction was associated with good predictive ability, with a C-index of 0.887(95% CI: 0.793-0.981) and an AUC of 0.924 (95% CI: 0.882-0.965).

CONCLUSION

SUVmax, the neutrophil-lymphocyte ratio, the platelet-lymphocyte ratio, initial TPSA, and clinical T-stage represent valuable independent predictors of lymph node metastasis in prostate cancer patients, offering an opportunity to further optimize lymph node staging for these patients.

Validating the screening criteria for bone metastases in treatment-naïve unfavorable intermediate and high-risk prostate cancer - the prevalence and location of bone- and lymph node metastases

OBJECTIVE

The European Association of Urology (EAU) recommends a bone scan for newly diagnosed unfavorable intermediate- and high-risk prostate cancer. We aimed to validate the screening criteria for bone metastases in patients with treatment-naïve prostate cancer.

METHODS

This single-center retrospective study included all patients with treatment-naïve unfavorable intermediate- or high-risk prostate cancer. All underwent MRI of the lumbar column (T2Dixon) and pelvis (3DT2w, DWI, and T2 Dixon). The presence and location of lymph node and bone metastases were registered according to risk groups and radiological (rad) T-stage. The risk of lymph node metastases was assessed by odds ratio (OR).

RESULTS

We included 390 patients, of which 68% were high-risk and 32% were unfavorable intermediate-risk. In the high-risk group, the rate of regional- and non-regional lymph node metastases was 11% and 6%, respectively, and the rate of bone metastases was 10%. In the unfavorable intermediate-risk group, the rate of regional- and non-regional lymph node metastases was 4% and 0.8%, respectively, and the rate of bone metastases was 0.8%. Metastases occurred exclusively in the lumbar column in 0.5% of all patients, in the pelvis in 4%, and the pelvis and lumbar column in 3%. All patients with bone metastases had radT3-4, and patients with radT3-4 showed a four-fold increased risk of lymph node metastases (OR 4.48, 95% CI: 2.1-9.5).

CONCLUSION

Bone metastases were found in 10% with high-risk prostate cancer and 0.8% with unfavorable intermediate-risk. Therefore, we question the recommendation to screen the unfavorable intermediate-risk group for bone metastases.

KEY POINTS

• The rate of bone metastases was 10% in high-risk patients and 0.8% in the unfavorable intermediate-risk group. • The rate of lymph-node metastases was 17% in high-risk patients and 5% in the unfavorable intermediate-risk group. • No bone metastases were seen in radiologically localized disease.

[High risk localized and locally advanced prostate cancer: Long-term oncological outcomes after prostatectomy]

INTRODUCTION

High risk localized and locally advanced forms are responsible for the vast majority of specific deaths from prostate cancer among non-metastatic diseases at diagnosis. No randomized study has yet been published to establish the best local treatment in terms of survival.

AIM

Conduct a large-volume cohort study with long-term follow-up to analyze specific and overall survival outcomes after surgery.

METHOD

A single-center retrospective study of all patients operated on for localized high-risk and locally advanced prostate cancer was performed. Actuarial survival analyses and multivariate analyses were performed to discern predictive risk factors.

RESULTS

Five hundred patients were included. MRI stage was≥iT3a in 40.7% of cases and 50.2% of patients had a Gleason score≥8 on biopsy. The mean follow-up was 63.1 months. The overall, specific and biological recurrence-free survival were respectively 77.6%, 93.9% and 26.8% at 10 years. A PSA level≥20, a Gleason score on biopsy≥9 and a MRI stage≥iT3a were significantly associated with the 10-years biological recurrence risk.

CONCLUSION

This study shows very good long-term oncological results. In the absence of a randomized controlled trial, these results suggest the primary role of surgery in this indication and support the evolution of current practices. We pointed out very pejorative features that might help selection of the best candidates for surgical treatment.

LEVEL OF EVIDENCE: 4

Comparing the Diagnostic Performance of Multiparametric Prostate MRI Versus 68Ga-PSMA PET-CT in the Evaluation Lymph Node Involvement and Extraprostatic Extension

PURPOSE

Our research aims to compare the efficacy of PET and MRI for lymph node metastasis and extraprostatic extension in cases with newly diagnosed prostate cancer undergoing radical prostatectomy with extended pelvic lymph node dissection.

METHODS

Thirty-nine cases who underwent radical prostatectomy with pelvic lymph node dissection between June 2015 and January 2020 were included in the study. Patients with gallium (ga-68 Prostate-specific membrane antigen (PSMA) PET) PSMA PET-CT and multiparametric (mp) prostate MRI performed according to PIRADS v2 criteria in our clinic were included.

RESULTS

The extraprostatic extension was observed in 16 cases. The sensitivity of MR in detecting extracapsular invasion was calculated as 56.2%, specificity 82.6%, positive predictive value (PPV) 69.2%, negative predictive value (NPV) 73.0%. The sensitivity of PET was 62.5%, specificity 60.8%, PPV 52.6%, NPV 70%. Eleven lymph node metastases were observed in nine cases. The sensitivity, specificity, PPV and NPV of metastatic lymph node detection were; 36.3%, 99.6%, 57.1%, 99.0% for MRI and; 18.1%, 99.4%, 33.3%, 98.8% for PET CT, respectively.

CONCLUSION

Mp prostate MRI showed low sensitivity and high specificity compared to PSMA PET CT in extracapsular invasion evaluation. The sensitivity of both modalities in the detection of metastatic lymph nodes was low.

Current Opinion on the Use of Magnetic Resonance Imaging in Staging Prostate Cancer: A Narrative Review

Accurate staging is critical for treatment planning and prognosis in men with prostate Cancer. Prostate magnetic imaging resonance (MRI) may aid in the staging evaluation by verifying organ-confined status, assessing the status of the pelvic lymph nodes, and establishing the local extent of the tumor in patients being considered for therapy. MRI has a high specificity for diagnosing extracapsular extension, and therefore may impact the decision to perform nerve sparing prostatectomy, along with seminal vesicle invasion and lymph node metastases; however, its sensitivity remains limited. Current guidelines vary significantly regarding endorsing the use of MRI for staging locoregional disease. For high-risk prostate cancer, most guidelines recommend cross sectional imaging, including MRI, to evaluate for more extensive disease that may merit change in radiation field, extended androgen deprivation therapy, or guiding surgical planning. Although MRI offers reasonable performance characteristics to evaluate bone metastases, guidelines continue to support the use of bone scintigraphy. Emerging imaging technologies, including coupling positron emission tomography (PET) with MRI, have the potential to improve the accuracy of prostate cancer staging with the use of novel radiotracers.

External Validation and Comparison of Two Nomograms Predicting the Probability of Lymph Node Involvement in Patients subjected to Robot-Assisted Radical Prostatectomy and Concomitant Lymph Node Dissection: A Single Tertiary Center Experience in the MRI-Era

Introduction

To externally validate and directly compare the performance of the Briganti 2012 and Briganti 2019 nomograms as predictors of lymph node invasion (LNI) in a cohort of patients treated with robot-assisted radical prostatectomy (RARP) and extended pelvic lymph node dissection (ePLND).

Materials and Methods

After the exclusion of patients with incomplete biopsy, imaging, or clinical data, 752 patients who underwent RARP and ePLND between December 2014 to August 2021 at our center, were included. Among these patients, 327 (43.5%) had undergone multi-parametric MRI (mpMRI) and mpMRI-targeted biopsy. The preoperative risk of LNI was calculated for all patients using the Briganti 2012 nomogram, while the Briganti 2019 nomogram was used only in patients who had performed mpMRI with the combination of targeted and systematic biopsy. The performances of Briganti 2012 and 2019 models were evaluated using the area under the receiver-operating characteristics curve analysis, calibrations plot, and decision curve analysis.

Results

A median of 13 (IQR 9–18) nodes per patient was removed, and 78 (10.4%) patients had LNI at final pathology. The area under the curves (AUCs) for Briganti 2012 and 2019 were 0.84 and 0.82, respectively. The calibration plots showed a good correlation between the predicted probabilities and the observed proportion of LNI for both models, with a slight tendency to underestimation. The decision curve analysis (DCA) of the two models was similar, with a slightly higher net benefit for Briganti 2012 nomogram. In patients receiving both systematic- and targeted-biopsy, the Briganti 2012 accuracy was 0.85, and no significant difference was found between the AUCs of 2012 and 2019 nomograms (p = 0.296). In the sub-cohort of 518 (68.9%) intermediate-risk PCa patients, the Briganti 2012 nomogram outperforms the 2019 model in terms of accuracy (0.82 vs. 0.77), calibration curve, and net benefit at DCA.

Conclusion

The direct comparison of the two nomograms showed that the most updated nomogram, which included MRI and MRI-targeted biopsy data, was not significantly more accurate than the 2012 model in the prediction of LNI, suggesting a negligible role of mpMRI in the current population.

Integration of Prostate Biopsy Results with Pre-Biopsy Multiparametric Magnetic Resonance Imaging Findings Improves Local Staging of Prostate Cancer

PURPOSE

To assess the added value of histological information for local staging of prostate cancer (PCa) by comparing the accuracy of multiparametric MRI alone (mpMRI) and mpMRI with biopsy Gleason grade (mpMRI+Bx).

METHODS

133 consecutive patients who underwent preoperative 3T-MRI and subsequent radical prostatectomy for PCa were included in this single-centre retrospective study. mpMRI imaging was reviewed independently by two uroradiologists for the presence of extracapsular extension (ECE) and seminal vesicle invasion (SVI) on a 5-point Likert scale. For second reads, the radiologists received results of targeted fused MR/US biopsy (mpMRI+Bx) prior to re-staging.

RESULTS

The median patient age was 63 years (interquartile range (IQR) 58-67 years) and median PSA was 6.5 ng/mL (IQR 5.0-10.0 ng/mL). Extracapsular extension was present in 85/133 (63.9%) patients and SVI was present in 22/133 (16.5%) patients. For ECE prediction, mpMRI showed sensitivity and specificity of 63.5% and 81.3%, respectively, compared to 77.7% and 81.3% achieved by mpMRI+Bx. At an optimal cut-off value of Likert score ≥ 3, areas under the curves (AUCs) was .85 for mpMRI+Bx and .78 for mpMRI, P < .01. For SVI prediction, AUC was .95 for mpMRI+Bx compared to .92 for mpMRI; P = .20. Inter-reader agreement for ECE and SVI prediction was substantial for mpMRI (k range, .78-.79) and mpMRI+Bx (k range, .74-.79).

CONCLUSIONS

MpMRI+Bx showed superior diagnostic performance with an increased sensitivity for ECE prediction but no significant difference for SVI prediction. Inter-reader agreement was substantial for both protocols. Integration of biopsy information adds value when staging prostate mpMRI.

Imaging of Prostate Cancer

BACKGROUND

Prostate cancer is the most common type of solid tumor in men and the second most common cause of cancer-related death in males in Germany. The conventional strategy for its primary detection, i.e., systematic ultrasound-guided prostate biopsy in men who have elevated PSA levels and/or positive findings on digital rectal examination, fails to reveal all cases. The same is true of the use of conventional computed tomography (CT), magnetic resonance imaging (MRI), and skeletal scintigraphy for the early detection of recurrences and distant metastases.

METHODS

This review is based on pertinent publications retrieved by a selective search, including the German clinical practice guideline on prostate cancer and systematic review articles.

RESULTS

Prospective multicenter trials have shown that the detection of clinically significant prostate cancer is markedly improved with multiparametric MRI (mpMRI) and MR/TRUS fusion biopsy (TRUS = transrectal ultrasonography), compared to conventional systematic biopsy. A recent Cochrane review showed that the rate of overdiagnosis of low-risk prostate cancer was reduced with mpMRI and MR/TRUS fusion biopsy compared with conventional systematic biopsy (95/1000 vs. 139/1000), and that clinically significant prostate cancer was more reliably detected (sensitivity 72% vs. 63%), albeit with slightly lower specificity (96% vs. 100%). Prostate-specific membrane antigen (PSMA) hybrid imaging improves the detection of lymphogenic and bony metastases in patients with high-risk prostate cancer. PSMA hybrid imaging is most commonly used to detect biochemical recurrences. A meta-analysis showed that the detection rate depends on the PSA concentration: 74.1% overall, 33.7% with PSA <0.2 ng/mL, and 91.7% with PSA ≥ 2.0 ng/mL.

CONCLUSION

The appropriate use of mpMRI and MR/TRUS fusion biopsy improves the initial detection of prostate cancer as well as the assessment of the prognosis. PSMA hybrid imaging is useful for the staging of high-risk patients and for the detection of recurrences. These methods are now recommended in the German clinical practice guideline on prostate cancer as well as in guidelines from other countries.

Comparison of 68Ga-labeled Prostate-specific Membrane Antigen Ligand Positron Emission Tomography/Magnetic Resonance Imaging and Positron Emission Tomography/Computed Tomography for Primary Staging of Prostate Cancer: A Systematic Review and Meta-analysis

Context

In December 2020, the US Food and Drug Administration approved a ⁶⁸Ga-labeled prostate-specific membrane antigen ligand (⁶⁸Ga-PSMA-11) for positron emission tomography (PET) in patients with suspected prostate cancer (PCa) metastasis who are candidates for initial definitive therapy. ⁶⁸Ga-PSMA PET is increasingly performed for these patients and is usually combined with computed tomography (CT). In recent years, ⁶⁸Ga-PSMA PET has been combined with high-resolution magnetic resonance imaging (MRI), which is beneficial for T staging and may further enhance the staging of primary PCa.

Objective

To compare the diagnostic accuracy of ⁶⁸Ga-PSMA PET/MRI with ⁶⁸Ga-PSMA PET/CT for staging of primary PCa.

Evidence acquisition

A comprehensive literature search was performed using Embase, PubMed/Medline, Web of Science, Cochrane Library, and Google Scholar up to June 24, 2021 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Risk of bias was assessed using the QUADAS-2 tool.

Evidence synthesis

The search identified 2632 articles, of which 27 were included. The diagnostic accuracy of ⁶⁸Ga-PSMA PET/MRI, measured as the pooled natural logarithm of diagnostic odds ratio (lnDOR), was 2.27 (95% confidence interval [CI] 1.21–3.32) for detection of extracapsular extension (ECE), 3.50 (95% CI 2.14–4.86) for seminal vesicle invasion (SVI), and 4.73 (95% CI 2.93–6.52) for lymph node metastasis (LNM). For ⁶⁸Ga-PSMA PET/CT, the analysis showed lnDOR of 2.45 (95% CI 0.75–4.14), 2.94 (95% CI 2.26–3.63), and 2.42 (95% CI 2.07–2.78) for detection of ECE, SVI, and LNM, respectively. The overall risk of bias and applicability concerns were assessed as moderate and low, respectively.

Conclusions

⁶⁸Ga-PSMA PET/MRI shows high diagnostic accuracy equivalent to that of ⁶⁸Ga-PSMA PET/CT for detection of ECE, SVI, and LNM in staging of PCa. There is an urgent need for direct comparison of the two diagnostic tests in future research.

Patient summary

The use of radioactively labeled molecules that bind to prostate-specific membrane antigen (⁶⁸Ga-PSMA) for positron emission tomography (PET) scans combined with either computed tomography (CT) or magnetic resonance imaging (MRI) is increasing for prostate cancer diagnosis. There is a need for direct comparison of the two tests to demonstrate the benefit of ⁶⁸Ga-PSMA PET/MRI for determining tumor stage in prostate cancer.

Take  Home Message

After the recent US Food and Drug Administration approval of ⁶⁸Ga-labeled prostate-specific membrane antigen ligand (⁶⁸Ga-PSMA) positron emission tomography (PET) for staging of primary prostate cancer (PCa), it is expected that the use of this imaging modality will increase rapidly. Our review of the literature shows that ⁶⁸Ga-PSMA PET/magnetic resonance imaging has high diagnostic accuracy equivalent to that of ⁶⁸Ga-PSMA PET/computed tomography in primary PCa staging. There is an urgent need for direct head-to-head comparison of the two diagnostic tests in future research.

MRI features of the normal prostatic peripheral zone: the relationship between age and signal heterogeneity on T2WI, DWI, and DCE sequences

OBJECTIVES

To assess the multiparametric MRI (mpMRI) appearances of normal peripheral zone (PZ) across age groups in a biopsy-naïve population, where prostate cancer (PCa) was subsequently excluded, and propose a scoring system for background PZ changes.

METHODS

This retrospective study included 175 consecutive biopsy-naïve patients (40-74 years) referred with a suspicion of PCa, but with subsequent negative investigations. Patients were grouped by age into categories ≤ 54, 55-59, 60-64, and ≥ 65 years. MpMRI sequences (T2-weighted imaging [T2WI], diffusion-weighted imaging [DWI]/apparent diffusion coefficient [ADC], and dynamic contrast-enhanced imaging [DCE]) were independently evaluated by two uro-radiologists on a proposed 4-point grading scale for background change on each sequence, wherein score 1 mirrored PIRADS-1 change and score 4 represented diffuse background change. Peripheral zone T2WI signal intensity and ADC values were also analyzed for trends relating to age.

RESULTS

There was a negative correlation between age and assigned background PZ scores for each mpMRI sequence: T2WI: r = - 0.52, DWI: r = - 0.49, DCE: r = - 0.45, p < 0.001. Patients aged ≤ 54 years had mean scores of 3.0 (T2WI), 2.7 (DWI), and 3.1 (DCE), whilst patients ≥ 65 years had significantly lower mean scores of 1.7, 1.4, and 1.9, respectively. There was moderate inter-reader agreement for all scores (range κ = 0.43-0.58). Statistically significant positive correlations were found for age versus normalized T2WI signal intensity (r = 0.2, p = 0.009) and age versus ADC values (r = 0.33, p = 0.001).

CONCLUSION

The normal PZ in younger patients (≤ 54 years) demonstrates significantly lower T2WI signal intensity, lower ADC values, and diffuse enhancement on DCE, which may hinder diagnostic interpretation in these patients. The proposed standardized PZ background scoring system may help convey the potential for diagnostic uncertainty to clinicians.

KEY POINTS

• Significant, positive correlations were found between increasing age and higher normalized T2-weighted signal intensity and mean ADC values of the prostatic peripheral zone. • Younger men exhibit lower T2-weighted imaging signal intensity, lower ADC values, and diffuse enhancement on dynamic contrast-enhanced imaging, which may hinder MRI interpretation. • A scoring system is proposed which aims towards a standardized assessment of the normal background PZ. This may help convey the potential for diagnostic uncertainty to clinicians.

Assessing ISUP prostate cancer grade groups in patients treated with definitive dose escalated external beam radiation

PURPOSE

The five grade group system has been validated for men treated with radical prostatectomy. However, the prognostic value for men treated with radiation therapy is uncertain, with prior studies utilising old techniques and doses. We aimed to validate the International Society of Urological Pathology (ISUP) groupings for men treated with contemporary radiation therapy.

METHODS

Men with localised prostate cancer treated with image-guided, dose-escalated (≥78 Gy) external beam radiation were identified across four institutions. Primary outcome was time to biochemical failure. Harrell's C index assessed performance of the ISUP system against other grading stratifications.

RESULTS

2205 men were included, withmedian follow-up of 5.6 years. Seven-year actuarial rates of biochemical failure for grade groups 1-5 were 9.3%, 10.4%, 13.2%, 12.4% and 23.4%. On multivariate analysis, hazard ratios for biochemical failure were1.19, 1.00, 1.10, 1.05 and 2.10 for grade groups 1-5, relative to 2. P values were only significant for grade group 5. Harrell's C index favoured an alternative three group model (comprising Gleason scores [6 and 3 + 4 = 7] vs [4 + 3 = 7 and 8] vs [9 and 10]) over ISUP grade groups.

CONCLUSIONS

The ISUP grade groups were not validated in a contemporary cohort treated with dose-escalated, image-guided radiation therapy. Grade groups 1-4 were not statistically different from each other; however, grade group 5 had a significantly worse prognosis. We identified a new three group model that better predicted biochemical outcomes. Further work is requiredto validate optimal groupings for modern radiation therapy and investigate the contrasting prognostic capability of grade groups in surgical and radiation therapy patients.

Evaluation of image-based prognostic parameters of post-prostatectomy urinary incontinence: A literature review

Prostate cancer is the second most common male cancer, and radical prostatectomy is a highly effective treatment for intermediate and high-risk disease. However, post-prostatectomy urinary incontinence remains a major functional side-effect in patients undergoing radical prostatectomy. Despite recent improvements in preoperative imaging quality and surgical techniques, it remains challenging to predict or prevent occurrence of this complication. The aim of this research was to review the current published literature on pre- and postoperative imaging evaluation of the prostate and pelvic structures, to identify added value in the prediction of post-prostatectomy urinary incontinence. A computerized bibliographic search of the PubMed library was carried out to identify imaging-based articles evaluating the pelvic floor and surrounding structures pre- and/or postradical prostatectomy to predict post-prostatectomy urinary incontinence. A total of 32 articles were included. Of these, 29 papers assessed the importance of magnetic resonance imaging evaluation, with a total of 16 parameters evaluated. The most common parameters were intravesical protrusion, the membranous urethral length, prostatic volume and periurethral fibrosis. Preoperative membranous urethral length and its preservation after surgery showed the strongest correlation with urinary incontinence. Three studies evaluated ultrasound, with all carried out postoperatively. This technique benefits from a dynamic evaluation, and the results are promising for proximal urethral hypermobility and the degree of bladder neck funneling on the Valsalva maneuver. Several imaging studies evaluated the predictors of post-prostatectomy urinary incontinence, with preoperative membranous urethral length offering the most promise. However, the current literature is limited by the single-center nature of studies, and the heterogeneity in patient populations and methodologies used.

Magnetic resonance imaging improves the prediction of tumor staging in localized prostate cancer

OBJECTIVES

The aim of this study was to investigate 3 Tesla multiparametric magnetic resonance imaging (mpMRI)-based predictors for the pretherapeutic T staging of prostate cancer and their accuracy.

METHODS

Consecutive patients with 3 Tesla mpMRI, positive systematic and MR-targeted biopsy, and subsequent radical prostatectomy (RPE) between 01/2016 and 12/2017 were included. MRI parameters such as measurable extraprostatic extension (EPE) (≥ 3 mm), length of (pseudo)capsular contact (LCC), invasion of neurovascular bundle (NVBI), and/or seminal vesicles lesion contact (SVC) or infiltration (SVI) were assessed and correlated to clinical and histopathological results.

RESULTS

136 men were included. In 76 cases, a pT2 stage was determined, in 29 cases a pT3a, and in 31 a pT3b stage. The positive and negative predictive values (PPV, NPV) for the detection of T3 by measurable EPE on MRI was 98% (CI 0.88-1) and 81% (CI 0.72-0.87). No visible NVBI was found in pT2 patients (NPV 100%; CI 0.95-1). ROC analysis for T3a prediction with LCC (AUC 0.81) showed a sensitivity of 87% and a specificity of 62% at a threshold of 12.5 mm (J = 0.485) and 93% and 58% at 11 mm (Jmax = 0.512). All patients with pT3a had a LCC > 5 mm. In case of pT3b, 29/31 patients showed a SVC (PPV 76%, CI 0.61-0.87; NPV 98%, CI 0.93-0.99), and 23/31 patients showed a SVI (PPV 100%, CI 0.86-1; NPV 93%, CI 0.87-0.96). EPE (p < 0.01), LCC (p = 0.05), and SVC (p = 0.01) were independent predictors of pT3.

CONCLUSIONS

MRI-measurable EPE, LCC, and SVC were reliable, independent, preoperative predictors for a histopathological T3 stage. A LCC ≥ 11 mm indicated a pT3a stage, whereas a LCC < 5 mm excluded it. On MRI, visible SVI or even SVC of the PCa lesion was reliable preoperative predictors for a pT3b stage.

Comparison of biparametric versus multiparametric prostate MRI for the detection of extracapsular extension and seminal vesicle invasion in biopsy naïve patients

PURPOSE

To compare biparametric MRI (bpMRI) with multiparametric MRI (mpMRI) staging accuracy in assessing extracapsular extension (ECE) and seminal vesicle invasion (SVI).

METHOD

Biopsy-naïve patients undergoing 3 T-MRI before radical prostatectomy for clinically significant prostate cancer were included in this single-centre retrospective study. Two uroradiologists separately evaluated bpMRI and mpMRI for presence of ECE and SVI using a 5-point Likert scale (1: ECE/SVI highly unlikely, 5: ECE/SVI highly likely).

RESULTS

110 men of median age 63 years and PSA 8.5 ng/mL were included. ECE and SVI was confirmed histologically in 71/110 (64.5 %) and 18/110 (16.4 %) patients, respectively. Sensitivity and specificity of bpMRI versus mpMRI for predicting ECE was 59.1 % and 87.2 % versus 66.2 % and 84.6 %, respectively. For SVI detection, the sensitivity and specificity for bpMRI versus mpMRI was 66.7 % and 92.4 % versus 83.3 % and 97.8 %, respectively. At an optimal cut-off Likert score ≥3 for ECE prediction, mpMRI area under the receiver operating curve (AUC) was 0.80 (95 % confidence interval (CI) 0.72-0.87) versus 0.78 (95 % CI 0.69-0.86) for bpMRI (p = 0.52) and for SVI, mpMRI AUC was 0.91 (95 % CI 0.84-0.96) versus 0.86 (95 % CI 0.78-0.92) for bpMRI (p = 0.02), respectively. Inter-reader agreement for both ECE and SVI prediction was substantial, with a marginally higher k-value for mpMRI (k range, 0.67-0.75) than bpMRI (k range, 0.65-0.69).

CONCLUSIONS

Diagnostic performance of bpMRI and mpMRI was comparable for detection of ECE, however, mpMRI with contrast was superior for SVI detection and improved the inter-reader agreement.

MRI-derived PRECISE scores for predicting pathologically-confirmed radiological progression in prostate cancer patients on active surveillance

OBJECTIVES

To assess the predictive value and correlation to pathological progression of the Prostate Cancer Radiological Estimation of Change in Sequential Evaluation (PRECISE) scoring system in the follow-up of prostate cancer (PCa) patients on active surveillance (AS).

METHODS

A total of 295 men enrolled on an AS programme between 2011 and 2018 were included. Baseline multiparametric magnetic resonance imaging (mpMRI) was performed at AS entry to guide biopsy. The follow-up mpMRI studies were prospectively reported by two sub-specialist uroradiologists with 10 years and 13 years of experience. PRECISE scores were dichotomized at the cut-off value of 4, and the sensitivity, specificity, positive predictive value and negative predictive value were calculated. Diagnostic performance was further quantified by using area under the receiver operating curve (AUC) which was based on the results of targeted MRI-US fusion biopsy. Univariate analysis using Cox regression was performed to assess which baseline clinical and mpMRI parameters were related to disease progression on AS.

RESULTS

Progression rate of the cohort was 13.9% (41/295) over a median follow-up of 52 months. With a cut-off value of category ≥ 4, the PRECISE scoring system showed sensitivity, specificity, PPV and NPV for predicting progression on AS of 0.76, 0.89, 0.52 and 0.96, respectively. The AUC was 0.82 (95% CI = 0.74-0.90). Prostate-specific antigen density (PSA-D), Likert lesion score and index lesion size were the only significant baseline predictors of progression (each p < 0.05).

CONCLUSION

The PRECISE scoring system showed good overall performance, and the high NPV may help limit the number of follow-up biopsies required in patients on AS.

KEY POINTS

• PRECISE scores 1-3 have high NPV which could reduce the need for re-biopsy during active surveillance. • PRECISE scores 4-5 have moderate PPV and should trigger either close monitoring or re-biopsy. • Three baseline predictors (PSA density, lesion size and Likert score) have a significant impact on the progression-free survival (PFS) time.

Whole-body magnetic resonance imaging for prostate cancer assessment: Current status and future directions

Over the past decade, updated definitions for the different stages of prostate cancer and risk for distant disease, along with the advent of new therapies, have remarkably changed the management of patients. The two expectations from imaging are accurate staging and appropriate assessment of disease response to therapies. Modern, next-generation imaging (NGI) modalities, including whole-body magnetic resonance imaging (WB-MRI) and nuclear medicine (most often prostate-specific membrane antigen [PSMA] positron emission tomography [PET]/computed tomography [CT]) bring added value to these imaging tasks. WB-MRI has proven its superiority over bone scintigraphy (BS) and CT for the detection of distant metastasis, also providing reliable evaluations of disease response to treatment. Comparison of the effectiveness of WB-MRI and molecular nuclear imaging techniques with regard to indications and the definition of their respective/complementary roles in clinical practice is ongoing. This paper illustrates the evolution of WB-MRI imaging protocols, defines the current state-of-the art, and highlights the latest developments and future challenges. The paper presents and discusses WB-MRI indications in the care pathway of men with prostate cancer in specific key situations: response assessment of metastatic disease, "all in one" cancer staging, and oligometastatic disease.

Attitudes and perceptions towards multiparametric magnetic resonance imaging of the prostate: A national survey among Italian urologists

OBJECTIVE

We aimed to assess the attitudes and perceptions towards multiparametric magnetic resonance imaging (mpMRI) of the prostate among Italian urologists.

MATERIAL AND METHODS

A national, web-based survey was performed. A questionnaire composed of 18 multiple choice questions was e-mailed to 941 currently active urologists, members of the Italian Society of Urology. Preserving anonymity, respondents' demographics were collected (e.g. geographic region, type of workplace, prostate procedures performed) as well as data concerning their attitudes and perceptions towards mpMRI (e.g. indications deemed appropriate, degree of confidence in mpMRI results). Data were expressed as raw numbers and percentages of survey answers.

RESULTS

In total, 98 responses were received (participation rate = 10.4%). Respondents mostly worked in urban areas (96%) and primarily in hospital settings (89%), while 48% of them worked in southern Italy. 97% of respondents considered mpMRI useful to detect Prostate Cancer (PCa) in patients with prior negative biopsy, 64% in biopsy-naïve patients and 60% for PCa pre-operatory staging. About half (42%) of the participants declared that mpMRI results frequently lead them to change PCa management strategy. Standardization of mpMRI acquisition and reporting was partially unsatisfactory. Reported waiting time for mpMRI scans was longer than 4 weeks for 51% of respondents. The major limitation of this survey includes the small number of participants.

CONCLUSIONS

Prostate mpMRI is used by Italian urologists mainly for detection and for pre-operative staging of PCa. Further improvements in terms of mpMRI availability and report standardization are required.

Multiparametric Magnetic Resonance Imaging Should Be Preferred Over Digital Rectal Examination for Prostate Cancer Local Staging and Disease Risk Classification

OBJECTIVE

To assess the impact of multiparametric magnetic resonance imaging (mp-MRI) local tumor staging on prostate cancer risk stratification and choice of treatment.

MATERIALS AND METHODS

Prostate cancer patients, newly diagnosed from 2017 to 2018 at 7 Dutch teaching hospitals were included. Risk group classification was done twice, using either digital rectal examination (DRE) or mp-MRI information. Risk group migration and rates of treatment intensification associated with mp-MRI upstaging were established. Diagnostic accuracy measures for the detection of nonorgan-confined disease (stage ≥T3a), for both DRE and mp-MRI, were assessed in patients undergoing robot-assisted radical prostatectomy.

RESULTS

A total of 1683 patients were included. Upstaging due to mp-MRI staging occurred in 493 of 1683 (29%) patients and downstaging in 43 of 1683 (3%) patients. Upstaging was associated with significant higher odds for treatment intensification (odds ratio [OR]: 3.5 95% confidence interval [CI] 1.9-6.5). Stage ≥T3a on mp-MRI was the most common reason for risk group upstaging (77%). Sensitivity for the detection of stage ≥T3a was higher for mp-MRI compared to DRE (51% vs 12%, P <.001), whereas specificity was lower (82% vs 97%, P <.001). Mp-MRI resulted in a significantly higher cumulative rate of true positive and true negative stage ≥T3a predictions compared with DRE (67% vs 58%, P <.001).

CONCLUSION

Use of mp-MRI tumor stage for prostate cancer risk classification leads to upstaging in 1 of 3 patients. Mp-MRI enables superior detection of nonorgan-confined disease compared with DRE, and should be the preferred tool for determining clinical tumor stage.

Development and External Validation of a Novel Nomogram to Predict Side-specific Extraprostatic Extension in Patients with Prostate Cancer Undergoing Radical Prostatectomy

BACKGROUND

Prediction of side-specific extraprostatic extension (EPE) is crucial in selecting patients for nerve-sparing radical prostatectomy (RP).

OBJECTIVE

To develop and externally validate nomograms including multiparametric magnetic resonance imaging (mpMRI) information to predict side-specific EPE.

DESIGN, SETTING, AND PARTICIPANTS

A retrospective analysis of 1870 consecutive prostate cancer patients who underwent robot-assisted RP from 2014 to 2018 at three institutions.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Four multivariable logistic regression models were established, including combinations of patient-based and side-specific variables: prostate-specific antigen (PSA) density, highest ipsilateral International Society of Urological Pathology (ISUP) biopsy grade, ipsilateral percentage of positive cores on systematic biopsy, and side-specific clinical stage assessed by both digital rectal examination and mpMRI. Discrimination (area under the curve [AUC]), calibration, and net benefit of these models were assessed in the development cohort and two external validation cohorts.

RESULTS AND LIMITATIONS

On external validation, AUCs of the four models ranged from 0.80 (95% confidence interval [CI] 0.68-0.88) to 0.83 (95% CI 0.72-0.90) in cohort 1 and from 0.77 (95% CI 0.62-0.87) to 0.78 (95% CI 0.64-0.88) in cohort 2. The three models including mpMRI staging information resulted in relatively higher AUCs compared with the model without mpMRI information. No major differences between the four models regarding net benefit were established. The model based on PSA density, ISUP grade, and mpMRI T stage was superior in terms of calibration. Using this model with a cut-off of 20%, 1980/2908 (68%) prostatic lobes without EPE would be found eligible for nerve sparing, whereas non-nerve sparing would be advised in 642/832 (77%) lobes with EPE.

CONCLUSIONS

Our analysis resulted in a simple and robust nomogram for the prediction of side-specific EPE, which should be used to select patients for nerve-sparing RP.

PATIENT SUMMARY

We developed a prediction model that can be used to assess accurately the likelihood of tumour extension outside the prostate. This tool can guide patient selection for safe nerve-sparing surgery.

Locally advanced prostate cancer imaging findings and implications for treatment from the surgical perspective

The anatomy of the prostate is reviewed in the context of discussing the staging of prostate cancer and patterns of tumor spread. The utility of prostate magnetic resonance imaging along with new advancements in tumor staging are discussed specifically in locally advanced disease. What should be included in the radiology report carries a substantial weight to formulate the urologist's decision in regards to the selection of surgical candidates, preoperative planning and avoiding postoperative complications.

PI-RADS score is associated with biochemical control and distant metastasis in men with intermediate-risk and high-risk prostate cancer treated with radiation therapy

BACKGROUND

Novel methods of risk stratification are needed for men with prostate cancer. The Prostate Imaging Reporting and Data System (PI-RADS) uses multiparametric MRI (mpMRI) to assign a score indicating the likelihood of clinically significant prostate cancer. We evaluated pretreatment mpMRI findings, including PI-RADS score, as a marker for outcome in patients treated with primary radiation therapy (RT).

METHODS

One hundred and twenty-three men, 64% and 36% of whom had National Comprehensive Cancer Network (NCCN) intermediate-risk and high-risk disease, respectively, underwent mpMRI prior to RT. PI-RADS score and size of the largest nodule were analyzed with respect to freedom from biochemical failure (FFBF) and freedom from distant metastasis.

RESULTS

A PI-RADS score of ≤3, 4, or 5 was defined in 7%, 49%, and 44%; with a median nodule size of 0, 8, and 18 mm, respectively (P < 0.001). Median follow-up was 67 months. Men with PI-RADS ≤ 3, 4, or 5 disease had 7-year FFBF of 100%, 92%, and 65% (P = 0.002), and a 7-year freedom from distant metastasis of 100%, 100%, and 82%, respectively (P = 0.014). PI-RADS (Hazard Ratio 5.4 for PI-RADS 5 vs. 4, P = 0.006) remained associated with FFBF when controlling for NCCN risk category (P = 0.063) and receipt of androgen deprivation therapy (P = 0.535). Nodule size was also associated with FFBF (Hazard Ratio 1.08 per mm, P < 0.001) after controlling for NCCN risk category (P = 0.156) and receipt of androgen deprivation therapy (P = 0.776).

CONCLUSION

mpMRI findings, including PI-RADS score and nodule size, may improve risk stratification in men treated with primary RT.